Conventionally, there has been a technology in which a window with a transparent background is provided so as to make an image behind the window observable (see Patent documents 1 to 4). There has been another technology of issuing position coordinates which are designated in a window of an operation target, to another window (see Patent document 5). There has been further another technology of moving a transparent control panel by following up a change in image pickup position of a camera (see Patent document 6).    [Patent document 1] JP 6-124183 A    [Patent document 2] JP 10-116174 A    [Patent document 3] JP 6-51738 A    [Patent document 4] JP 04-045487 A    [Patent document 5] JP 2006-244078 A    [Patent document 6] JP 9-9137 A